1. Field of the Invention
The present invention relates to a method of fabricating a molding, and more particularly to a method of fabricating a molding which high-frequency heats the longitudinal end of a workpiece extruded by extrusion and thereafter molds the workpiece into a molding having a prescribed shape.
2. Description of Related Art
A method of fabricating a molding such as a side molding for a motor vehicle is previously known wherein resin material is extruded into a predetermined sectional shape by an extrusion machine, the material is cooled and cut into segments each having a predetermined length and, both longitudinal ends of each segment is set in a metallic mold of an injection molding machine and both ends are integrally molded to have predetermined shapes. The molding fabricated by this method is shown in FIGS. 8(a) and (b).
FIGS. 8(a) and (b) show the end of a molding fabricated by the conventional molding fabrication method; FIG. 8(a) is a partial plan view thereof and FIG. 8(b) is a partial sectional view.
In these drawings, generally, a molding body 1 is successively extruded by extrusion, and its plane shown in FIG. 8(a) cut in a predetermined length constitutes a design plane. An end 2 is formed on the tip of the molding body 1 by injection molding, and one or both ends of the molding body 1 successively extruded by extrusion are finished in a predetermined design.
The above conventional molding fabricating method provides a difference in shape between the extrusion orifice of an extrusion machine and the cavity of an injection molding metallic mold whose shapes define the sectional shapes of the molding body 1 and the end 2, and a variation in material or size between the molding body 1 and the end 2. Such difference or variation results in a connection line, burrs or level difference between the molding body 1 and the end 2 so that in some cases, a beautiful design plane cannot be obtained therebetween.
Such poor appearance in the design plane between the molding body 1 and the end 2 is remarkable in surface treatment increasing a sink on the side of the junction surface 2a of the end 2, in which both are colored, a shining film is bonded, etc.
To solve the aforementioned problem, a molding fabricating method has been proposed in which the end of a long workpiece extruded by an extrusion machine is previously softened by heating and the end of the workpiece in the softened state, is molded into a desired shape.
In this case, the end of the workpiece is heated by a high frequency heating machine including upper and lower electrodes. However, the upper and lower electrodes are formed in a relatively large scale so as to permit moldings having various kinds of specifications. For this reason, when the end of the workpiece is heated, the adjacent portions as well as the end may be heated, thus reducing the heating efficiency and resulting in non-uniform heating of the end.